Fixed edge cases & add'l type support

• Fixed numerous edge cases
  • Improved exception handling
  • Resolved cyclical type issues
  • Access violations resolved
• Additional type support
  • Enum and Enumeration types fixed
  • Support for Guid and DateTime graph-types
  • User defined graph-type issues fixed
• Added add'l exception handling
  • More defined exceptions added
  • MSIL bugs resolved
  • Unit tests improved + add'l cases added